Energy transfer and trapping in photosystem I with and without chlorophyll- f

Ivo H M van Stokkum; Marc G Müller; Jörn Weißenborn; Sebastian Weigand; Joris J Snellenburg; Alfred R Holzwarth

doi:10.1016/j.isci.2023.107650

Energy transfer and trapping in photosystem I with and without chlorophyll- f

iScience. 2023 Aug 15;26(9):107650. doi: 10.1016/j.isci.2023.107650. eCollection 2023 Sep 15.

Authors

Ivo H M van Stokkum¹, Marc G Müller², Jörn Weißenborn¹, Sebastian Weigand¹, Joris J Snellenburg¹, Alfred R Holzwarth^{1

2}

Affiliations

¹ Department of Physics and Astronomy and LaserLaB, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, Amsterdam 1081 HV, the Netherlands.
² Max-Planck-Institut für chemische Energiekonversion, 45470 Mülheim a.d. Ruhr, Germany.

Abstract

We establish a general kinetic scheme for energy transfer and trapping in the photosystem I (PSI) of cyanobacteria grown under white light (WL) or far-red light (FRL) conditions. With the help of simultaneous target analysis of all emission and transient absorption datasets measured in five cyanobacterial strains, we resolved the spectral and kinetic properties of the different species present in PSI. WL-PSI can be described by Bulk Chl a, two Red Chl a, and a reaction center compartment (WL-RC). The FRL-PSI contains two additional Chl f compartments. The lowest excited state of the FRL-RC is downshifted by ≈ 29 nm. The rate of charge separation drops from ≈900 ns^-1 in WL-RC to ≈300 ns^-1 in FRL-RC. The delayed trapping in the FRL-PSI (≈130 ps) is explained by uphill energy transfer from the Chl f compartments with Gibbs free energies of ≈k_BT below that of the FRL-RC.

Keywords: Biochemistry; Biophysics; Chemistry; Theoretical chemistry; Theoretical photochemistry.